[5] If the heart rate is too high, cardiac output may fall due to the markedly reduced ventricular filling time.

[6] Rapid rates, though they may be compensating for ischemia elsewhere, increase myocardial oxygen demand and reduce coronary blood flow, thus precipitating an ischemic heart or valvular disease.

[9][10] Notable in McArdle Disease (GSD-V) is the phenomenon of second wind where after approximately 6–10 minutes of aerobic exercise, such as walking without an incline, the heart rate drops as blood borne fuels, predominantly from free fatty acids, produce energy via oxidative phosphorylation.

Beta blockers may be used to decrease tachycardia in patients with certain conditions, such as ischemic heart disease and rate-related angina.

In patients with inappropriate sinus tachycardia, careful titration of beta-blockers, salt loading, and hydration typically reduce symptoms.

Patients with sustained sinus tachycardia reflects a larger infarct that are more anterior with prominent left ventricular dysfunction, associated with high mortality and morbidity.

Tachycardia in the presence of AMI can reduce coronary blood flow and increase myocardial oxygen demand, aggravating the situation.